1. A primary function will be to supply investigators within the Program Project with genetically defined strains of rats. The facility will continue to breed and make available three strains of animals: Inbred Spontaneously Hypertensive Rats (SHR); Inbred Wistar-Kyoto Rats (WKY- CR); Outbred Wistar-Kyoto Rats (WKY-TF) and will commence selective and limited inbreeding of the WKY_TF. 2. The Core will continue successive cross-breeding paradigms which will include the following: F1 progeny from an SHR X WKY cross to be used for further breeding; F2 progeny from an F1 X F1 cross to be used for studies, and Backcross (BC) Progeny from an F1XSHR cross for study. 3. The Core will breed progeny from recombinant F2-derived Brown Norway X SHR rats from breeding pairs obtained from Czechoslovakia. All animals will be used for studies. 4. The Core will perform several duties in support of the above operations and in support of Program Investigators which include the following services: tail-cuff systolic pressure determination for breeder selection; phenotype determination of cardiac startle responses in intercross and backcross progeny for subsequent studies and molecular genetics; direct arterial blood pressure measurements in awake conscious, unstressed adult rats; assist other investigators with direct blood pressure measurements; assist Program Investigators in meeting Animal Subjects requirements and monitor compliance by all Program Investigators with Animal Subjects requirements when using Core animals. Finally, Core B will work closely with Core C n genetic quality control measurements.